In a nuclear plant, the reactor and fuel storage pools contain pure water and the overall environment in the pools are to be kept as clean as possible. However, when for example the reactor is in use, a certain amount of radioactive debris and particles, such as crud from the fuel rods or metal chips from wear on reactor components, circulate in the pool and water system and will deposit on surfaces such as floor surfaces and wall surfaces of pools and pipes.
These surfaces need to be cleaned at certain predetermined intervals in order to maintain a high level of cleanliness. The normal procedure is to empty the water from the pools and to clean the surfaces manually with mechanical cleaning devices such as brushes or sponges as well as with high pressure water.
Certain objections have been raised regarding these cleaning methods because they are time consuming and expose workers to radiation. It is also important to clean these surfaces as much as possible since aerosols are liberated when lowering the water level. This may adversely affect persons in this environment and demands have been made to reduce the exposure due to contaminants introduced into in the environment by aerosol.
A number of devices have been developed that may perform cleaning of surfaces with reduced labour and also without the need to empty the pools. However, these types of devices are specifically designed to move around on the floor and cannot be used on vertical surfaces. Other types of cleaning devices are designed for cleaning vertical walls, but do require additional equipment in order to be able to move around, such as lifting devices.
In general the devices developed are not suited for nuclear environments, i.e. chemical, mechanical and electrical requirements on equipment and material to be used in the nuclear environment. Thus there are still improvements to be made in this area.